In situ Formed Mesoporous Silver Nanowire Electrocatalysts for Efficient CO2 Electrolysis

Abstract

Electrochemical CO2 reduction at high current densities is often limited by electrolyte flooding and competitive hydrogen evolution reaction (HER) on catalysts with insufficient surface hydrophobicity. Herein, we report organic-ligand-free in situ formed mesoporous Ag nanowires (Ag NWs), in which the porous architecture maintains a morphology-driven partial-wetting state that provides abundant electrolyte-accessible active sites while preserving efficient CO2 transport pathways. To achieve this structure, we develop a facile nanostructuring strategy based on sequential vapor-phase iodination and controlled electrochemical reduction of Ag. We reveal that the reduction rate governs the growth pathway and determines the architecture of catalysts: slow reduction promotes anisotropic nanowire formation, whereas rapid reduction yields short, randomly oriented Ag nanodendrites. The in situ formed Ag NWs achieve a high CO Faradaic efficiency of 98.9% at -1.06 V vs. the reversible hydrogen electrode (RHE) and maintain stable performance for over 300 h at a current density of 100 mA cm-2, while sustaining a low H2 Faradaic efficiency of 2.63% even at 400 mA cm-2. These findings demonstrate the critical role of mesoporous surface architectures in regulating interfacial wetting and CO2 mass transport, establishing a facile and broadly applicable strategy for designing high-performance Ag-based CO2 reduction electrocatalysts.